lhs preload is always a single preload, so just preload one

1 files changed, 3 insertions, 3 deletions

diff --git a/activerecord/lib/active_record/associations/preloader.rb b/activerecord/lib/active_record/associations/preloader.rb
index dca7179953..1be5de708e 100644
--- a/activerecord/lib/active_record/associations/preloader.rb
+++ b/activerecord/lib/active_record/associations/preloader.rb
@@ -112,10 +112,10 @@ module ActiveRecord
       end
 
       def preload_hash(association)
-        association.each do |parent, child|
-          Preloader.new(records, parent, preload_scope).run
+        association.flat_map { |parent, child|
+          preload_one parent
           Preloader.new(records.map { |record| record.send(parent) }.flatten, child).run
-        end
+        }
       end
 
       # Not all records have the same class, so group then preload group on the reflection